A possible stumbling block for peace talks on Syria this morning. Overnight, US Secretary General Ban Ki-Moon invited Iran to the talks which are set to start on Wednesday in Geneva. But the move has drawn strong objections.

"Over the weekend there was some sens of muted celebration that the Syrian opposition had agreed to attend these peace talks in Geneva, the first real talks of their kind during this now 3 year long brutal civil war. But, just as though joy had begun to establish itself, Ban Ki-Moon extended this invitation to Iran," CNN's Nick Paton Walsh reports.